In the field of integrated optics, there may be a need to transfer a signal carried by one waveguide, for example, a single-mode wave-guide, to another waveguide, for example, a multi-mode waveguide, where the signal may be carried by one of a plurality of modes, each of a different order, or vice versa. One known way of doing so includes establishing a periodic perturbation using a static device designed to provide long period grating in the multimode waveguide, thereby to couple co-propagating modes. Among the drawbacks of this solution are its sensitivity to fabrication parameters and a difficulty in coupling modes residing in different waveguides. Another known method to convert a signal carried by a single-mode waveguide to be carried by a mode of a multi-mode waveguide is using an adiabatic asymmetric Y-branch. The drawbacks of this solution include the critical manufacturing tolerances of the device, and the poor separation between the divided modes leading to coupling and/or cross talk between the modes. A further known way to achieve mode-conversion is using a multi-mode interference converter; however, this solution has low conversion efficiency.